1. Field of the Invention
This invention relates to key devices for vehicles and more particularly to a vehicle key device suitable for preventing a vehicle from being stolen.
A vehicle such as an automobile is sometimes stolen when the operator forgets to lock the vehicle. However, a vehicle may still be illicitly unlocked and stolen, even when it has been locked.
2. Description of the Prior Art
Means for preventing a vehicle lock from being released, thereby preventing the theft of a vehicle, have been proposed by Japanese Application Publication No. 2991/1966, Japanese Patent Application (OPI) No. 81239/1984 (the term "OPI" as used herein means "an unexamined published application"). Such a device is, however, disadvantageous in that the reliability in reading the data may be decreased in case of a contact fault of the bar code board, since the data printed on the board are read in a contact mode. To overcome this difficulty, the following device has been proposed by Japanese Patent Application (OPI) No. 72867/1985. In the device, light is applied to a bar code board on which predetermined data have been printed. Detection of an optical signal from the bar code board releases the lock of a vehicle door or steering wheel. With the device, the data can be read even in a non-contact mode. Therefore, the above-described difficulty with vehicle key devices that employ contact means can be eliminated. However, the above-described device in which the data printed on the bar code board are read as optical signals is still disadvantageous because it may fail to function when dust sticks on the bar code board or when the bar code board is inserted at high speed.